TIFFMEDIAN(1)                                       TIFFMEDIAN(1)

NAME
       tiffmedian  -  apply the median cut algorithm to data in a
       TIFF file

SYNOPSIS
       tiffmedian [ options ] input.tif output.tif

DESCRIPTION
       tiffmedian applys the median cut algorithm to an RGB image
       in  input.tif  to generate a palette image that is written
       to output.tif.  The generated colormap  has,  by  default,
       256  entries.  The image data is quantized by mapping each
       pixel to the closest color values in the colormap.

OPTIONS
       -c     Specify the compression to use for data written  to
              the  output file: none for no compression, packbits
              for PackBits  compression,  lzw  for  Lempel-Ziv  &
              Welch compression, and zip for Deflate compression.
              By default tiffmedian will compress data  according
              to  the  value  of the Compression tag found in the
              source file.

              LZW compression can be specified  together  with  a
              predictor  value.   A  predictor  value of 2 causes
              each scanline of the output image to undergo  hori-
              zontal  differencing  before it is encoded; a value
              of 1 forces each scanline  to  be  encoded  without
              differencing.   LZW-specific  options are specified
              by appending a ``:''-separated list to the  ``lzw''
              option;  e.g.   -c  lzw:2  for LZW compression with
              horizontal differencing.

       -C     Specify the number of entries to use in the  gener-
              ated  colormap.   By default all 256 entries/colors
              are used.

       -f     Apply Floyd-Steinberg dithering before selecting  a
              colormap entry.

       -r     Specify  the  number  of  rows  (scanlines) in each
              strip of data  written  to  the  output  file.   By
              default,  tiffmedian attempts to set the rows/strip
              that no more than 8 kilobytes of data appear  in  a
              strip.

NOTES
       This  program  is derived from Paul Heckbert's median pro-
       gram.

SEE ALSO
       pal2rgb(1), tiffinfo(1), tiffcp(1), tiffcmp(1), libtiff(3)

       "Color  Image Quantization for Frame Buffer Display", Paul
       Heckbert, SIGGRAPH proceedings, 1982, pp. 297-307.

                         October 15, 1995                       1